The present invention relates to a liquid filling valve which is used to fill a liquid into a vessel while the interior of the vessel is sealed, and in particular, to a filling valve employed in a filler which can be selectively used with a bottle-like vessel of a smaller mouth aperture (referred to hereafter as a first type vessel) such as a vessel or bottle which-can be resealed with a cap as exemplified by a PET bottle and also with a vessel having a larger aperture such as a canister (hereinafter referred to as a second type vessel).
Generally a filler is provided with a filling valve which comprises a filled liquid passage formed within a valve body, and a liquid valve which opens or closes the filled liquid passage. By opening the liquid valve, the liquid to be filled is injected into the vessel through the filled liquid passage. When the filler is used to fill a carbonic acid gas-charged beverage into a vessel, it is necessary to seal a top opening of the vessel and accordingly, a centering guide which guides the top opening of the vessel and a gasket which seals the top opening are used in bringing the gasket into abutment under pressure against the full periphery of the top opening of the vessel in order to seal the interior of the vessel while the beverage is being filled.
The bottle-like first type vessel and the second type vessel, such as a canister, have different aperture diameters for a mouth or top opening. Accordingly, when a filler of the type as mentioned above in which a filling operation takes place by sealing the mouth of the vessel is to be selectively used with both types of vessels, the gasket which seals the interior of the vessel and the centering guide must be changed depending on the type of vessels.
Accordingly, in order to allow the filler to be selectively used with vessels with different mouth apertures, there is proposed a combined use filling valve (see US Patent No. 3,455,350) including a first gasket which is adapted to be disposed in abutment against the mouth of the first type vessel of a smaller mouth aperture, such as a bottle, and a second gasket which is adapted to be disposed in abutment against the mouth of the second type vessel of a larger aperture, such as a can. In the arrangement of this patent, when the type of the vessel is changed, there is no need to change a cylindrical member on which a gasket is mounted, and it is only necessary to change a vent tube.
In the arrangement of the cited patent, when the second type vessel of a larger aperture, such as a canister, is to be filled, in particular, when a canister having a reduced wall thickness is to be filled, it is to be noted that there arises a problem that an imbalance between a force applied from a filling valve and a force from the vessel prevents a seal from being successfully achieved because the aperture of the canister which is sealed by the gasket associated with the canister is greatly different from the aperture of the filling valve. In addition, if the gasket is forcibly urged against the vessel in order to achieve a reliable seal, there occurs a deformation of the vessel.
To cope with this problem, the inventors of the present Application have previously filed a Patent Application for a filling valve which allows a combined use with the bottle-like first type vessel and a second type vessel having a larger aperture, such as a can, and which is capable of achieving a balance between the force from the vessel and the force from the filling valve during the filling operation without requiring a replacement of parts as the vessel type is changed (see Japanese Laid-Open Patent Publication No. 2002-370,797).
The arrangement of a filling valve disclosed in the cited Application will be described briefly below with reference to FIGS. 4A and 4B. A filling valve 101 includes a valve body 102 in which a filled liquid passage 104 is formed, which is opened and closed by a liquid valve 108. The liquid valve 108 comprises a valve element 112 formed on the bottom end of a rod 110 which is inserted into the filled liquid passage 104 in an elevatable manner, and a valve seat 114 formed on the internal surface of the filled liquid passage 104 at the bottom thereof.
In order to achieve a suitable load when sealing the mouth of a vessel when filling into the bottle-like first type vessel B and the second type vessel C having a larger opening aperture, the valve body 102 of the filling valve 101 is formed with a larger diameter portion 102a and a smaller diameter portion 102b, and a vessel mouth gasket unit 132 is correspondingly formed with a larger diameter portion 132a and a smaller diameter portion 132b which fit around the larger diameter portion 102a and the smaller diameter portion 102b, respectively. A first seal member 134 which seals between the larger diameter portions 102a and 132a and a second seal member 136 which seals between the smaller diameter portions 102b and 132b are provided, and a first gasket 138 which substantially matches the aperture diameter of the bottle-like first type vessel B and a second gasket 140 which substantially matches the aperture diameter of the second type vessel C, such as a canister, are amounted on the bottom surface of the vessel mouth gasket unit 132. For the first type vessel B, a filling operation takes place by bringing the smaller diameter portions 102b and 132b into fitting engagement (see FIG. 4A) while for the second type vessel C, a filling operation takes place while removing the smaller diameter portions 102b and 132b from each other (see FIG. 4B).
In a conventional arrangement, when filling the bottom-like first type vessel B, there has been a need to provide a gas passage 152 which communicates with a space 156 (see FIG. 4A) defined between the first seal member 134 and the second seal member 136 as well as a valve, not shown, which operates to open or close the passage 152 in order to allow a flow of the air into and out of the space 156 during the elevating motion of the vessel mouth gasket unit 132. In addition, the gas passage 152 needs to be cleaned, resulting in complicating the structure.